Browsing by Subject "High-speed AM"
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Item Reactive Extrusion Additive Manufacturing (REAM) with applications to magnetically actuated shape memory thermoset composites(2021-12-03) Uitz, Oliver Liam; Seepersad, Carolyn; Tehrani, Mehran; Crawford, Richard H; Ounaies, ZoubeidaResearch in the field of additive manufacturing (AM) is increasingly focused on the use of novel material feedstocks and deposition processes to augment the functionality of AM parts. Such efforts have led to the incorporation of functional grading and shape memory capabilities into AM processes and parts which, for example, can support the fabrication of active structures that respond to specific stimuli. This work seeks to couple these techniques and features with a novel additive process called “reactive extrusion.” In reactive extrusion additive manufacturing (REAM), successive layers of thermoset resin are mixed with a curing agent, deposited, and rapidly cured in situ. The resulting parts are largely isotropic due to interlayer crosslinking of polymer chains and have mechanical properties superior to those of typical thermoplastic AM parts. By using thermosetting resin feedstocks with selectively embedded magnetically active ferromagnetic particles, the proposed REAM system will be capable of creating composite parts with remotely activated shape-change capabilities. By heating targeted domains of the composite above the glass transition temperature of the polymer matrix, the composite becomes capable of low strain-energy deformation by virtue of its increased compliance. Subsequent exposure to an external magnetic field will induce deformation within the part dependent on the placement of the embedded ferromagnetic particles, as well as the strength, gradient, and alignment of the external magnetic field. This magnetically induced deformation will then be fixed by cooling the part below the glass transition temperature of the polymer matrix, permitting service of the deformed part in sufficiently cool environments. Reheating of the part above its glass transition temperature will return the part to its original, as-manufactured shape, allowing the geometry to be reprogrammed repeatedly. The use of thermosetting resin affords the user a wide range of material choices when creating parts, from stiff epoxies to compliant urethanes. Such a system would be capable of creating parts and components for a wide array of applications that would otherwise necessitate manufacturing multiple parts/components of different sizes, e.g. children’s prosthetics, custom orthotics, and other products whose geometries need periodic adjustment.